Mad Cow Disease: Transmission

Prion diseases attack nervous system tissue. Prions have been associated with Bovine Spongiform Encephalopathy (BSE), Creutzfeldt-Jakob Disease (CJD), and variant Creutzfeldt-Jakob Disease (vCJD). Neither viruses nor bacteria, prions are thought to be proteins with abnormal shapes. Prions enter the body when people eat beef products that contain infected nervous system tissue. Once in the body, prions are believed to convert normal proteins in the nervous system into the abnormal prion shape.

Prions duplicate by attaching themselves to, and changing the structure of, normal proteins. It is believed that when a person eats the brain, spinal cord or other nervous system tissue from an infected animal, prions are absorbed into the body, where they slowly begin to transform normal proteins, eventually leading to fatal damage to the nervous system.